Methods for bonding structural elements of paper machine and industrial fabrics to one another and fabrics produced thereby

ABSTRACT

A method of manufacturing and a papermaker&#39;s or industrial fabric, which includes the application of a polymeric resin material onto preselected discrete locations on a base substrate in a controlled manner in droplets having an average diameter of 10μ (10 microns) to point bond yarns, bond spiral wound strips together or to bond layers of a fabric together.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of U.S. patent application Ser. No.11/342,184 filed Jan. 27, 2006 entitled “Methods for Bonding StructuralElements of Paper Machine and Industrial Fabrics to One Another andFabrics Produced Thereby” which is a division of U.S. patent applicationSer. No. 10/334,249 filed Dec. 31, 2002, now U.S. Pat. No. 7,022,208granted Apr. 4, 2006, the enclosures of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, in part, to the papermaking arts, andspecifically to the fabrics, commonly referred to as paper machineclothing, on which paper is manufactured on paper machines. The presentinvention also relates to the manufacture of nonwoven articles andproducts by processes such as hydroentanglement, and specifically to theso-called industrial fabrics on which such articles are manufactured.More specifically still, the present invention concerns the bonding ofstructural elements, such as individual yarns or separate layers, ofsuch fabrics to one another by methods in which polymeric resinmaterials are used as bonding agents and are deposited in a highlycontrolled and precise manner.

2. Description of the Prior Art

During the papermaking process, a cellulosic fibrous web is formed bydepositing a fibrous slurry, that is, an aqueous dispersion of cellulosefibers, onto a moving forming fabric in the forming section of a papermachine. A large amount of water is drained from the slurry through theforming fabric, leaving the cellulosic fibrous web on the surface of theforming fabric.

The newly formed cellulosic fibrous web proceeds from the formingsection to a press section, which includes a series of press nips. Thecellulosic fibrous web passes through the press nips supported by apress fabric, or, as is often the case, between two such press fabrics.In the press nips, the cellulosic fibrous web is subjected tocompressive forces which squeeze water therefrom, and which adhere thecellulosic fibers in the web to one another to turn the cellulosicfibrous web into a paper sheet. The water is accepted by the pressfabric or fabrics and, ideally, does not return to the paper sheet.

The paper sheet finally proceeds to a dryer section, which includes atleast one series of rotatable dryer drums or cylinders, which areinternally heated by steam. The newly formed paper sheet is directed ina serpentine path sequentially around each in the series of drums by adryer fabric, which holds the paper sheet closely against the surfacesof the drums. The heated drums reduce the water content of the papersheet to a desirable level through evaporation.

It should be appreciated that the forming, press and dryer fabrics alltake the form of endless loops on the paper machine and function in themanner of conveyors. It should further be appreciated that papermanufacture is a continuous process which proceeds at considerablespeeds. That is to say, the fibrous slurry is continuously depositedonto the forming fabric in the forming section, while a newlymanufactured paper sheet is continuously wound onto rolls after it exitsfrom the dryer section.

Contemporary fabrics are produced in a wide variety of styles designedto meet the requirements of the paper machines on which they areinstalled for the paper grades being manufactured. Generally, theycomprise a woven or other type base fabric. Additionally, as in the caseof fabrics used in the press section, the press fabrics have one or morebase fabrics into which has been needled a batt of fine, nonwovenfibrous material. The base fabrics may be woven from monofilament, pliedmonofilament, multifilament or plied multifilament yarns, and may besingle-layered, multi-layered or laminated. The yarns are typicallyextruded from any one of the synthetic polymeric resins, such aspolyamide and polyester resins, used for this purpose by those ofordinary skill in the paper machine clothing arts.

The woven base fabrics themselves take many different forms. Forexample, they may be woven endless, or flat woven and subsequentlyrendered into endless form with a woven seam. Alternatively, they may beproduced by a process commonly known as modified endless weaving,wherein the widthwise edges of the base fabric are provided with seamingloops using the machine-direction (MD) yarns thereof. In this process,the MD yarns weave continuously back-and-forth between the widthwiseedges of the fabric, at each edge turning back and forming a seamingloop. A base fabric produced in this fashion is placed into endless formduring installation on a paper machine, and for this reason is referredto as an on-machine-seamable fabric. To place such a fabric into endlessform, the two widthwise edges are brought together, the seaming loops atthe two edges are interdigitated with one another, and a seaming pin orpintle is directed through the passage formed by the interdigitatedseaming loops.

Further, the base fabrics may be laminated by placing at least one basefabric within the endless loop formed by another, and by typicallyneedling a staple fiber batt through these base fabrics to join them toone another as in the case of press fabrics. One or more of these wovenbase fabrics may be of the on-machine-seamable type. This is now a wellknown laminated press fabric with a multiple base support structure. Inany event, the fabrics are in the form of endless loops, or are seamableinto such forms, having a specific length, measured longitudinallytherearound, and a specific width, measured transversely thereacross.Also disclosed are “subassemblies” of various materials which are thenspiraled or laid up in parallel strips to form substrates for pressfabrics; the subassemblies are formed by techniques includinglamination.

Turning now to industrial process belts, laminated structures are knownin the textile industry. Lamination techniques are also used to formroll covers used in papermaking. One prior art belt is composed only ofnonwoven fibrous material as the substrate. Also previously disclosedare laminated nonwovens for use as press fabrics with each layer hasdifferent properties such as hydrophobicity, and multiple extrudedsheets as support structures for belts. Another prior patent teachesspirally winding strips of various types of materials to form a supportstructure for a belt. The prior art also teaches a substrate of expandedfilm, and narrow composite “tapes”. Additional prior art includes thefollowing:

U.S. Pat. No. 3,042,568 shows a method and apparatus for the manufactureof laminated fabric belting. A heating chamber and pressure rollers areused to bond a plurality of lengths of plastic-coated fabric into alaminated unitary belt;

U.S. Pat. No. 3,673,023 shows a process for producing a reinforcedlaminate for use in belts where high tensile strength is required. Thebelts are made by laying helically wound, continuous reinforcing cordsin what is essentially a screw thread or threads extending between thelateral margins of a base. The belt is finished by a top ply laid overthe wound carcass, which is then cured with heat and pressure to form aconsolidated belt structure;

U.S. Pat. No. 4,109,543 shows a composite laminate. The laminatecomprises a hot-melt-type thermoplastic material and a textile wovenfabric material formed of spun yarns constructed primarily of staplefibers. They are combined with each other using heat and pressure toform a belt; and

U.S. Pat. No. 5,240,531 shows an endless conveyor belt consisting of acore member and an elastic laminate layer. The layers are togetherpassed through a pressing apparatus that bonds them together through theuse of heat and pressure.

In the case of many applications, including woven fabrics, fabricsproduced by spirally winding a strip of woven or knitted fabric (seeU.S. Pat. No. 5,360,656 to Rexfelt), laminated fabrics all require somemechanism for either keeping the yarns in place or for joining thefabric together. Typically heretofor needling of staple fiber through amultilayer fabric was utilized to keep it together. Other methods asaforenoted were utilized such as bonding or welding.

The present invention provides another approach towards bonding andproviding dimensional stability to fabrics.

SUMMARY OF THE INVENTION

Accordingly, the present invention may find application in any of thefabrics used in the forming, pressing and drying sections of a papermachine, and in the industrial fabrics used in the manufacture ofnonwoven products. As such, the papermaker's or industrial fabriccomprises a base substrate which takes the form of an endless loop. Inone embodiment, a plurality of discrete, discontinuous deposits ofpolymeric resin material are disposed at the crossover points orlocations of the yarns in the fabric. These deposits bond the yarnstogether at these points and provide dimensional stability to thefabric.

The preselected locations for the discrete, discontinuous deposits ofpolymeric resin material may be where the yarns in one direction of thefabric pass over or under the yarns in the other direction. Bonding cantake place at all or just some of the crossover points.

In another embodiment, preselected locations may be used to joinadjacent steps of spiral wound fabric strip to one another.

In a third embodiment, the preselected locations for the bonding resinare knuckles formed by crossover yarns or other locations which willallow upon heating or other activating means to bond additional layersto the base fabric to create a laminate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an apparatus used to manufacturepapermaker's and industrial fabrics according to a first embodiment ofthe present invention;

FIG. 2 is a plan view of the surface of a fabric on which the firstembodiment may be practiced;

FIG. 3 is a plan view of the fabric shown in FIG. 2 following thepractice of the first embodiment thereon;

FIG. 4 is a schematic view of the apparatus shown in FIG. 1 as used inpracticing a second embodiment of the present invention;

FIG. 5 is a plan view of a portion of a seam between turns of a spirallywound fabric strip before bonding in accordance with the secondembodiment;

FIG. 6 is a plan view of the portion of the seam shown in FIG. 5following the practice of the second embodiment thereon;

FIG. 7 is a plan view of the surface of a base fabric used for thepractice of a third embodiment of the present invention; and

FIG. 8 is a schematic view of the apparatus shown in FIG. 1 as used inpracticing the third embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As stated above, in a first embodiment of the present invention, theyarns in a woven paper machine or industrial fabric are bonded to oneanother at their crossing points. Typically, the fabric, which may be abase substrate for a coated belt or some other item of paper machineclothing and which may be of an open weave in which the yarns would tendto shift from their intended positions unless bonded to one another inaccordance with the present invention, is woven from monofilament yarns.

More broadly, however, the fabric may be a woven, nonwoven, spiral-link,MD or CD yarn arrays, or knitted fabric comprising yarns of any of thevarieties used in the production of paper machine clothing or of theindustrial fabrics used to manufacture nonwoven articles and products,such as monofilament, plied monofilament, multifilament and pliedmultifilament yarns. These yarns may be obtained by extrusion from anyof the polymeric resin materials used for this purpose by those ofordinary skill in the art. Accordingly, resins from the families ofpolyamide, polyester, polyurethane, polyaramid, polyolefin and otherresins may be used.

Alternatively, the fabric may be produced by spirally winding a strip ofwoven, knitted or other material in accordance with the methods shown incommonly assigned U.S. Pat. No. 5,360,656 to Rexfelt et al., theteachings of which are incorporated herein by reference. The fabric mayaccordingly comprise a spirally wound strip, wherein each spiral turn isjoined to the next by a continuous seam making the fabric endless in alongitudinal direction. The joining of the spiral turns to one anothermay be accomplished in accordance with a second embodiment of thepresent invention to be discussed in greater detail below.

The above should not be considered to be the only possible forms for thefabric. Any of the varieties of fabric used by those of ordinary skillin the paper machine clothing and related arts may alternatively beused.

Whatever the specific form of the fabric, it is mounted on the apparatus10 shown schematically in FIG. 1, so that polymeric resin material maybe deposited onto the points where its yarns cross one another in eithera woven structure or nonwoven structure such as an MD or CD yarn array,in accordance with this first embodiment of the present invention.

It should be understood that the fabric may be either endless orseamable into endless form during installation on a paper machine. Assuch, the fabric 12 shown in FIG. 1 should be understood to be arelatively short portion of the entire length of the fabric. Where thefabric 12 is endless, it would most practically be mounted about a pairof rolls, not illustrated in the figure but most familiar to those ofordinary skill in the paper machine clothing arts. In such a situation,apparatus 10 would be disposed on one of the two runs, most convenientlythe top run, of the fabric 12 between the two roll. Whether endless ornot, however, the fabric 12 is preferably placed under an appropriatedegree of tension during the process. Moreover, to prevent sagging, thefabric 12 may be supported from below by a horizontal support member asit moves through apparatus 10. It should finally be observed that, wherethe fabric 12 is endless, it may be desirable to invert it, that is, toturn it inside out, following the application of polymeric resinmaterial in accordance with this first embodiment of the presentinvention to place the polymeric resin material on the backside of thefabric 12.

Referring now more specifically to FIG. 1, where the fabric 12 isindicated as moving in an upward direction through the apparatus 10 asthe method of this first embodiment of the present invention is beingcarried out, apparatus 10 comprises a sequence of several stationsthrough which the fabric 12 may pass incrementally.

The stations are identified as follows:

-   -   1. optional polymer deposition station 14;    -   2. imaging/precise polymer deposition station 24;    -   3. optional setting station 36; and    -   4. optional grinding station 44.

In the first station, the optional polymer deposition station 14, apiezojet array 16 mounted on transverse rails 18,20 and translatablethereon in a direction transverse to that of the motion of the fabric 12through the apparatus 10, as well as therebetween in a directionparallel to that of the motion of the fabric 12, may be used to deposita polymeric resin material in a repetitive fashion if necessary toprovide the proper bonding onto or within the fabric 12 while the fabric12 is at rest. Optional polymer deposition station 14 may be used todeposit the polymeric resin material more uniformly over the fabric 12than could be accomplished using conventional techniques, such asspraying, if desired. It should be understood, however, that theoptional polymer deposition station 14 would apply the polymeric resinmaterial indiscriminately to both the yarns of the fabric 12 and to thespaces or interstices between the yarns. This may not be desired in allapplications and, as such, the use of polymer deposition station 14 isoptional in this and other embodiments of the present invention.

However, for the sake of completeness, the piezojet array 16 comprisesat least one but preferably a plurality of individual computercontrolled piezojets, each functioning as a pump whose active componentis a piezoelectric element. As a practical matter, an array of up to 256piezojets or more may be utilized, if the technology permits. The activecomponent is a crystal or ceramic which is physically deformed by anapplied electric signal. This deformation enables the crystal or ceramicto function as a pump, which physically ejects a drop of a liquidmaterial each time an appropriate electric signal is received. As such,this method of using piezojets to supply drops of a desired material inresponse to computer controlled electric signals is commonly referred toas a “drop-on-demand” method.

Referring again to FIG. 1, the piezojet array 16, starting from an edgeof the fabric 12, or, preferably, from a reference thread extendinglengthwise therein, translates lengthwise and widthwise across thefabric 12, while the fabric 12 is at rest, deposits the polymeric resinmaterial in the form of extremely small droplets having a nominaldiameter of 10μ (10 microns) or more, such as 50μ (50 microns), or 100μ(100 microns), onto the fabric 12. The translation of the piezojet array16 lengthwise and widthwise relative to the fabric 12, and thedeposition of droplets of the polymeric resin material from eachpiezojet in the array 16, are controlled by computer to apply a desiredamount of the polymeric resin material per unit area of the fabric 12,if desired. In addition, the deposit of the material need not only betraversing the movement of the base substrate but can be parallel tosuch movement, spiral to such movement or in any other manner suitablefor the purpose.

In the present invention, in which a piezojet array is used to deposit apolymeric resin material onto or within the surface of the fabric basesubstrate 12, the choice of polymeric resin material is limited by therequirement that its viscosity be 100 cps (100 centipoise) or less atthe time of delivery, that is, when the polymeric resin material is inthe nozzle of a piezojet ready for deposition, so that the individualpiezojets can provide the polymeric resin material at a constant dropdelivery rate. A second requirement limiting the choice of polymericresin material is that it must partially set during its fall, as a drop,from a piezojet to the fabric 12, or after it lands on the fabric 12, toprevent the polymeric resin material from flowing and to maintaincontrol over the polymeric resin material to ensure that it remains inthe form of a drop where it lands on the fabric 12. Suitable polymericresin materials which meet these criteria are

-   -   1. Hot melts and moisture-cured hot melts;    -   2. Two-part reactive systems based on urethanes and epoxies;    -   3. Photopolymer compositions consisting of reactive acrylated        monomers and acrylated oligomers derived from urethanes,        polyesters, polyethers, and silicones; and    -   4. Aqueous-based latexes and dispersions and particle-filled        formulations including acrylics and polyurethanes.

It should be understood that the polymeric resin material needs to befixed on or within the fabric 12 following its deposition thereon. Themeans by which the polymeric resin material is set or fixed depends onits own physical and/or chemical requirements. Photopolymers are curedwith light, whereas hot-melt materials are set by cooling. Aqueous-basedlatexes and dispersions are dried and then cured with heat, and reactivesystems are cured by heat. Accordingly, the polymeric resin materialsmay be set by curing, cooling, drying or any combination thereof.

The proper fixing of the polymeric resin material is required to controlits penetration into and distribution within the fabric 12, that is, tocontrol and confine the material within the desired volume of the fabric12. Such control is important below the surface plane of the fabric 12to prevent wicking and spreading. Such control may be exercised, forexample, by maintaining the fabric 12 at a temperature which will causethe polymeric resin material to set quickly upon contact. Control mayalso be exercised by using such materials having well-known orwell-defined curing or reaction times on fabrics having a degree ofopenness such that the polymeric resin material will set before it hastime to spread beyond the desired volume of the fabric 12.

The degree of precision of the jet in depositing the material willdepend upon the dimensions and amount of the material being deposited.The type of jet used and the viscosity of the material being appliedwill also impact the precision of the jet selected.

When any desired amount of polymeric resin material has been applied perunit area in a band between the transverse rails 18,20 across the fabric12, if any, the fabric 12 is advanced lengthwise an amount equal to thewidth of the band, and the procedure described above is repeated toapply the polymeric resin material in a new band adjacent to thatpreviously completed. In this repetitive manner, the entire fabric 12can be provided with any desired amount of polymeric resin material perunit area.

One or more passes over the base substrate 12 may be made by piezojetarray 16 to deposit the desired amount of material and to create thedesired bond.

Alternatively, the piezojet array 16, again starting from an edge of thefabric 12, or, preferably, from a reference thread extending lengthwisetherein, is kept in a fixed position relative to the transverse rails18,20, while the fabric 12 moves beneath it, to apply any desired amountof the polymeric resin material per unit area repetitively so as toprovide bonding in a lengthwise strip around the fabric 12. Uponcompletion of the lengthwise strip, the piezojet array 16 is movedwidthwise on transverse rails 18,20 an amount equal to the width of thelengthwise strip, and the procedure described above is repeated to applythe polymeric resin material in a new lengthwise strip adjacent to thatpreviously completed. In this repetitive manner, the entire fabric 12can be provided with the desired amount of polymeric resin material perunit area, if desired.

At one end of the transverse rails 18,20, a jet check station 22 isprovided for testing the flow of polymeric resin material from eachpiezojet in the piezojet array 16. There, the piezojets can be purgedand cleaned to restore operation automatically to any malfunctioningpiezojet unit.

In the second station, the imaging/precise polymer deposition station24, the only station not optional in the present invention, transverserails 26,28 support a digital-imaging camera 30, which is translatableacross the width of fabric 12, and a piezojet array 32, which istranslatable both across the width of the fabric 12 and lengthwiserelative thereto between transverse rails 26,28, while the fabric 12 isat rest.

The digital-imaging camera 30 views the surface of the fabric 12 tolocate the locations where the material is to be deposited for bondingpurposes. For example, the knuckles where the yarns in one direction ofthe fabric 12 weave over those in the other direction may be thelocation points or where one yarn crosses the other in a nonwoven yarnarray may be another. Comparisons between the actual surface and itsdesired appearance are made by a fast pattern recognizer (FPR) processoroperating in conjunction with the digital-imaging camera 30. The FPRprocessor signals the piezojet array 32 to deposit polymeric resinmaterial onto the locations requiring it to match the desiredappearance. In this first embodiment of the present invention, thepolymeric resin material is deposited onto the yarns in a controlledmanner over the cross over location or where the knuckles are formed andadjacent to the respective yarns to bond the yarns to one another attheir crossing points. As in optional polymer deposition station 14, apiezojet check station 34 is provided at one end of the transverse rails26,28 for testing the flow of material from each piezojet. There, eachpiezojet in the piezojet array 32 can be purged and cleaned to restoreoperation automatically to any malfunctioning piezojet unit.

By way of illustration, FIG. 2 is a plan view of the surface of a fabric50, which is woven in a fairly open, plain weave from lengthwise yarns52 and crosswise yarns 54. Knuckles 56 are formed where lengthwise yarns52 pass over crosswise yarns 54 and where crosswise yarns 54 pass overlengthwise yarns 52. Because interstices 58 are relatively large, ameasure of the openness of the weave, it is straightforward to imaginethat the lengthwise and crosswise yarns 52,54 could readily shift fromthe idealized positions shown in FIG. 2 and that the fabric 50 may besomewhat sleazy.

FIG. 3 is a plan view of the surface of fabric 50 showing the manner inwhich polymeric resin material is deposited thereon in imaging/precisepolymer deposition station 24. On either side of each knuckle 56,polymeric resin material 60 is deposited on the lengthwise or crosswiseyarn 52,54 over which the knuckle 56 is formed to bond the two yarns52,54 to one another at the crossing point represented by the knuckle56.

In the third station, the optional setting station 36, transverse rails38,40 support a setting device 42, which may be required to set thepolymeric resin material being used. The setting device 42 may be a heatsource, for example, an infrared, hot air, microwave or laser source;cold air; or an ultraviolet or visible-light source, the choice beinggoverned by the requirements of the polymeric resin material being used.

Finally, the fourth and last station is the optional grinding station44, where an appropriate abrasive is used to provide any polymeric resinmaterial above the surface plane of the fabric 12 with a uniformthickness. The optional grinding station 44 may comprise a roll havingan abrasive surface, and another roll or backing surface on the otherside of the fabric 12 to ensure that the grinding will result in auniform thickness.

In a variation of the present invention, the optional polymer depositionstation 14, the imaging/precise polymer deposition station 24, and theoptional setting station 36 may be adapted to treat fabric 12 accordingto a spiral technique, rather than by indexing in the cross-machinedirection as described above. In a spiral technique, the optionalpolymer deposition station 14, the imaging/precise polymer depositionstation 24, and the optional setting station 36 start at one edge of thefabric 12, for example, the left-hand edge in FIG. 1, and are graduallymoved across the fabric 12, as the fabric 12 moves in the directionindicated in FIG. 1. The rates at which the stations 14,24,36 and thefabric 12 are moved are set so that the polymeric resin material desiredin the finished fabric is spiraled onto the fabric 12 as desired in acontinuous manner. In this alternative, the polymeric resin materialdeposited by the optional polymer deposition station 14 andimaging/precise polymer deposition station 24 may be partially set orfixed as each spiral passes beneath the optional setting device 42, andcompletely set when the entire fabric 12 has been processed through theapparatus 10.

Alternatively, the optional polymer deposition station 14, theimaging/precise polymer deposition station 24 and the optional settingstation 36 may all be kept in fixed positions aligned with one another,while the fabric 12 moves beneath them, so that the polymeric resinmaterial desired for the finished fabric may be applied to a lengthwisestrip around the fabric 12. Upon completion of the lengthwise strip, theoptional polymer deposition station 14, the imaging/precise polymerdeposition station 24 and the optional setting station 36 are movedwidthwise an amount equal to the width of the lengthwise strip, and theprocedure is repeated for a new lengthwise strip adjacent to thatpreviously completed. In this repetitive manner the entire fabric 12 canbe completely treated as desired.

Furthermore, the entire apparatus can remain in a fixed position withthe material processed. It should be noted that the material need not bea full width structure but can be a strip of material such as thatdisclosed in U.S. Pat. No. 5,360,656 to Rexfelt, the disclosure of whichis incorporated herein by reference, and subsequently formed into a fullwidth fabric. The strip can be unwound and wound up on a set of rollsafter fully processing. These rolls of fabric materials can be storedand can then be used to form an endless full width structure using, forexample, the teachings of the immediately aforementioned patent.

In this regard, a second embodiment of the present invention, apparatus10 is now used to bond adjacent turns of a spirally wound fabric stripto one another to form an endless fabric. A method for doing soemploying an ultrasonic welding apparatus is disclosed in commonlyassigned U.S. Pat. No. 5,713,399 to Collette et al., the teachings ofwhich are incorporated herein by reference.

More specifically, U.S. Pat. No. 5,713,399 discloses a method formanufacturing a papermaker's fabric by spirally winding a woven fabricstrip, narrower than the intended width of the fabric, and thepapermaker's fabric manufactured in accordance with the method. Thefabric strip includes lengthwise and crosswise yarns, and has a lateralfringe along at least one lateral edge thereof, the lateral fringe beingformed by unbound ends of the crosswise yarns extending beyond thelateral edge. During the spiral winding of the fringed strip, thelateral fringe of a turn overlies or underlies an adjacent turn of thestrip. The lateral edges of adjacent turns abut against one another. Thespirally continuous seam so obtained is closed by ultrasonically weldingor bonding the overlying or underlying lateral fringe to the fabricstrip in an adjacent turn.

Referring now to FIG. 4, which shows apparatus 10 as previously shown inFIG. 1, but adapted to practice this second embodiment of the presentinvention with the addition of a first roll 62 and a second roll 64,which are parallel to one another and which may be rotated in thedirections indicated by the arrows, a woven fabric strip 66 is woundfrom a stock roll 68 around the first roll 62 and the second roll 64 ina continuous spiral. It will be recognized that it will be necessary totranslate the stock roll 68 at a suitable rate along the second roll 64,that is, to the right in FIG. 4, as the fabric strip 66 is being woundaround the rolls 62,64.

Woven fabric strip 66 has a first lateral edge 70 and a second lateraledge 72. Extending beyond the woven fabric strip 66 along its first andsecond lateral edges 70,72 are a first and a second lateral fringe74,76, respectively, which are not shown in FIG. 4.

As woven fabric strip 66 is spirally wound around the first and secondrolls 62,64, its first lateral edge 70 is abutted against the secondlateral edge 72 of the previously wound turn to define a spirallycontinuous seam 78. Referring now to FIG. 5, which is a plan view of aportion of the seam 78 before any bonding has taken place, first lateralfringe 74 formed by unbound ends of crosswise yarns 80 extending pastlateral edge 70 overlies the previous turn of the woven fabric strip 66when the first and second lateral edges 70,72 are abutted against oneanother. Moreover, second lateral fringe 76 formed by unbound ends ofcrosswise yarns 80 extending past lateral edge 72 underlies thesubsequent turn of the woven fabric strip 66 when the first and secondlateral edges 70,72 are abutted against one another.

In accordance with this second embodiment of the present invention,imaging/precise polymer deposition station 24 is used to close thespirally continuous seam 78 instead of the ultrasonic welding apparatusshown in U.S. Pat. No. 5,713,399. Specifically, the digital imagingcamera 30 views the surface of the spirally wound woven fabric strip 66at the spirally continuous seam 78 to locate the points where thecrosswise yarns 80 of the first lateral fringe 74 overlying the previousturn of the woven fabric strip 66 cross the lengthwise yarns 82 therein,and to locate the points where the crosswise yarns 80 of the secondlateral fringe 76 underlying the subsequent turn of the woven fabricstrip 66 cross the lengthwise yarns 82 therein. Comparisons between theactual surface and its desired appearance are made by a fast patternrecognizer (FPR) processor operating in conjunction with thedigital-imaging camera 30. The FPR processor signals the piezojet array32 to deposit polymeric resin material onto the locations requiring itto match the desired appearance. In this second embodiment of thepresent invention, the polymeric resin material is deposited onto theunderlying yarn adjacent to the overlying yarn at the crossing points tobond the yarns to one another, thereby to close the spirally continuousseam 78.

FIG. 6 is a plan view of the portion of the seam 78 shown in FIG. 5after the bonding has been carried out. As shown, crosswise yarns 80 ofthe first lateral fringe 74 are bonded to the underlying lengthwiseyarns 82 by polymeric resin material 84 deposited onto the lengthwiseyarns 82 adjacent to crosswise yarns 80 by imaging/precise polymerdeposition station 24. Similarly, crosswise yarns 80 of second lateralfringe 76 are bonded to the overlying lengthwise yarns 82 by polymericresin material 84 deposited onto the crosswise yarns 80 adjacent tolengthwise yarns 82. In this manner, the spirally continuous seam 78 isclosed by imaging/precise polymer deposition station 24. Similarly, theapparatus can be used to bond an array of MD yarns (or CD yarns) to eachother. For example, an array of MD yarns is fed into the apparatusinstead of the Rexfelt strip of material. The piezojet then depositsresin at precise, discontinuous locations along the length of coincidentyarns in the space therebetween causing the yarns to bond to one anotherat that point. As the yarn array is fed into the apparatus, the piezojetwill traverse to the next set of MD yarns and continue as such until theappropriate length and width of fabric is created. Subsequent additionalpasses of the piezo jets can be made for additional deposits, if sodesired. Lengths of such fabric may be rolled up and stored forsubsequent use in creating a full width fabric or as a layer of alaminate.

In a third embodiment of the present invention, apparatus 10 is used tolaminate one fabric layer to another. A method for doing so is disclosedin commonly assigned U.S. Pat. No. 6,350,336 to Paquin, the teachings ofwhich are incorporated herein by reference. More specifically, U.S. Pat.No. 6,350,336 discloses a method for manufacturing a press fabric for apaper machine, which method includes the attachment of a strip of toplaminate layer material to a base fabric using a heat activated adhesivefilm. The top laminate layer material may be a woven fabric, a nonwovenmesh or a thermoplastic sheet material, and, in any case, has theheat-activated adhesive film bonded to one of its two sides. The stripof top laminate layer material and heat activated adhesive film togetherform a multi-component strip, which is spiraled onto the outer surfaceof the base fabric, with the side of the strip of top laminate layermaterial having the heat-activated adhesive film against the outersurface, in a closed helix, and bonded thereto with heat and pressure.The portions of the multi-component strip overhanging the lateral edgesof the base fabric are then trimmed and a staple fiber batt is needledinto and through the top laminate layer formed by the multi-componentstrip to firmly attach it to the base fabric.

In accordance with this third embodiment of the present invention,imaging/precise polymer deposition station 24 is used to apply athermoplastic polymeric resin material onto the knuckles formed wherethe yarns in one direction of the base fabric weave over those on theother direction.

Specifically, the digital-imaging camera 30 views the outer surface ofthe base fabric to locate the knuckles formed where the yarns in onedirection of the base fabric weave over those in the other direction.Comparisons between the actual surface and its desired appearance aremade by a fast pattern recognizer (FPR) processor operating inconjunction with the digital-imaging camera 30. The FPR processorsignals the piezojet array 32 to deposit polymeric resin material ontothe locations requiring it to match the desired appearance. In thisthird embodiment of the present invention, a thermoplastic polymericresin material is deposited onto the knuckles on the outer surface ofthe base fabric.

FIG. 7 is a plan view of the surface of the base fabric 90 as it couldappear following this deposition. Base fabric 90 is woven fromlengthwise yarns 92 and crosswise yarns 94 in a single-layer plainweave, although it should be understood that the inventors do not intendthe practice of the present invention to be limited to such a weave. Thelengthwise yarns 92 form knuckles 96 where they pass over crosswiseyarns 94. Similarly, the crosswise yarns 94 form knuckles 98 where theypass over lengthwise yarns 92. Knuckles 96,98 have a coating 100 ofthermoplastic polymeric resin material precisely applied thereto byimaging/precise polymer deposition station 24. Although each knuckle96,98 is shown to have such a coating 100, it need not be so, as it iswithin the scope of this third embodiment of the present invention toapply coating 100 only to certain preselected knuckles 96,98, whileleaving the remaining knuckles 96,98 uncoated.

Referring now to FIG. 8, which, like FIG. 4, shows apparatus 10 aspreviously shown in FIG. 1, but adapted to practice this thirdembodiment of the present invention with the addition of the first roll62 and the second roll 64, which are parallel to one another and whichmay be rotated in the directions indicated by the arrows. Base fabric 90remains entrained about the first and second rolls 62,64 following theapplication of coating 100 onto knuckles 96,98, and a strip 102 of toplaminate layer material is spirally wound thereon in a closed helix fromstock roll 68. The strip 102 of top laminate layer material may be, forexample, a woven fabric, a nonwoven mesh, MD or CD yarn arrays or athermoplastic sheet material. After the strip 102 of top laminate layermaterial is dispensed onto base fabric 90, it passes beneath the settingstation 36, which, for this third embodiment of the present invention,is a heat source which melts the thermoplastic polymeric resin materialon the knuckles 96,98 to adhere the strip 102 of top laminate layermaterial to the base fabric 90. The base fabric 90 and strip 102 thenpass together under the grinding station 44 which, functioning as aroll, presses them together while the thermoplastic polymeric resinmaterial resolidifies to bond them to one another. Such a laminate canbe the industrial fabric itself. Or, if required, needled batt can beapplied to one or more surfaces.

Modifications to the above would be obvious to those of ordinary skillin the art, but would not bring the invention so modified beyond thescope of the appended claims. For example, depending upon theapplication, it may be desirable to have some piezojets deposit onepolymeric resin material while others deposit a different polymericresin material. Also, while piezojets are disclosed above as being usedto deposit the material, in preselected locations on the base substrate,other means for depositing droplets thereof in the size range desiredmay be known to those of ordinary skill in the art or may be developedin the future, and such other means may be used in the practice of thepresent invention. The use of such means would not bring the invention,if practiced therewith, beyond the scope of the appended claims.

1. A method for manufacturing a papermaker's or industrial fabric, saidmethod comprising the steps of: a) providing a base substrate for thefabric comprising fabric strips having a lateral fringe comprising yarnsthat extend beyond a lateral edge wherein lateral edges of adjacentturns of fabric strip abut one another with the lateral fringe overlyingthe adjacent strip; b) depositing polymeric resin material on saidlateral fringe at a plurality of preselected discrete locations whereyarns of the lateral fringe overlap with yarns in an adjacent strip indroplets in a controlled manner to bond said yarns together and in turnthe fabric strip; and c) at least partially setting said polymeric resinmaterial.
 2. A method as claimed in claim 1 wherein said droplets have anominal diameter of 10μ (10 microns) or more.
 3. A method as claimed inclaim 1 wherein steps b) and c) are performed sequentially on successivebands extending widthwise across said base substrate.
 4. A method asclaimed in claim 1 wherein steps b) and c) are performed sequentially onsuccessive strips extending lengthwise around said base substrate.
 5. Amethod as claimed in claim 1 wherein steps b) and c) are performedspirally around said base substrate.
 6. A method as claimed in claim 1wherein said fabric strips include oppositely disposed lateral fringesand wherein lateral fringes of adjacent turns of fabric strips overlapwith the preselected discrete locations being at a plurality oflocations where respective yarns of the respective lateral fringesoverlap.
 7. A method as claimed in claim 1 wherein said polymeric resinmaterial is deposited in a random or uniform pattern.
 8. A method asclaimed in claim 1 wherein, in step b), said polymeric resin material isdeposited by a piezojet array comprising at least one computercontrolled piezojet.
 9. A method as claimed in claim 1 wherein step b)comprises the steps of: i) checking in real time the surface of saidbase substrate to locate the desired discrete crossover locations and tocause the deposit thereon of said polymeric resin material.
 10. A methodas claimed in claim 9 wherein said checking step is performed by a fastpattern recognizer (FPR) processor operating in conjunction with adigital-imaging camera in real time.
 11. A method as claimed in claim 10wherein said depositing step is performed by a piezojet array coupled tosaid FPR processor.
 12. A method as claimed in claim 1, wherein saidpolymeric resin material is selected from the group consisting of: 1.hot melts and moisture-cured hot melts;
 2. two-part reactive systemsbased on urethanes and epoxies;
 3. photopolymer compositions consistingof reactive acrylated monomers and acrylated oligomers derived fromurethanes, polyesters, polyethers, and silicones; and
 4. aqueous-basedlatexes and dispersions and particle-filled formulations includingacrylics and polyurethanes.
 13. A method as claimed in claim 1 whereinsaid curing step is performed by exposing said polymeric resin materialto a heat source, cold air or actinic acid.
 14. A method as claimed inclaim 8 wherein said piezojet array comprises a plurality of individualcomputer controlled piezojets, and wherein some of said individualcomputer controlled piezojets deposit one polymeric resin material whileother individual computer controlled piezojets deposit a differentpolymeric resin material.
 15. A method as claimed in claim 1 furthercomprising the optional step of abrading said polymeric resin materialdeposited to provide said polymeric resin material with a uniformthickness.
 16. A papermaker's or industrial fabric comprising of: a basesubstrate of the fabric comprising fabric strips having a lateral fringecomprising yarns that extend beyond a lateral edge wherein lateral edgesof adjacent turns of fabric strip abut one another with the lateralfringe overlying the adjacent strip; and polymeric resin materialdisposed on said lateral fringe at a plurality of preselected discretelocations where yarns of the lateral fringe overlap with yarns in anadjacent strip to bond said yarns together and in turn the fabric strip.17. A papermaker's or industrial fabric as claimed in claim 16 whereinsaid fabric strips include oppositely disposed lateral fringes andwherein lateral fringes of adjacent turns of fabric strips overlap withthe preselected discrete locations being of locations where respectiveyarns of respective lateral fringes overlap.